1. Field of the Invention
The invention relates to a printing device capable of increasing a printing speed, and more particularly to a printing device capable of automatically selecting a suitable sheet among a plurality of sheets placed in trays and quickly printing data on the sheet in a paper-jam-free manner.
2. Description of the Related Art
A conventional digital copier often includes multiple trays in response to different output demands. The dimension of the original may be detected, and the to-be-printed sheet satisfying the dimension of the original may be selected according to the detected result. Alternatively, the to-be-printed sheet and the scaling ratio may be selected manually such that the data can be printed on the to-be-printed sheet.
Although the digital copier has the function of enabling the user to select the desired sheet in the suitable tray or of automatically selecting a suitable sheet in the suitable tray, as disclosed in U.S. Pat. No. 5,323,212, the sheet-feeding mode corresponding to the maximum dimension of the printable sheet is the mode in which the sheet is fed longitudinally, such that the width of the copier may be minimized. For example, the typical copier usually has an A4-sized tray, in which A4-sized sheets may be placed, and an A3-sized tray, in which A3-sized sheets may be placed. The A4-sized tray may accommodate the longitudinal A4-sized sheets, each of which is longitudinally fed in a travelling direction extending in a lengthwise direction of the sheet. The A3-sized tray may accommodate the A3-sized sheets or the A4-sized sheets arranged transversally. The A4-sized sheets arranged transversally in the A3-sized tray are fed in a travelling direction extending in a widthwise direction of the sheet. When the longitudinal A4-sized sheet is being printed, the printing speed is low and the condition of paper jam tends to occur at the curved sheet passageway because the sheet stays in the sheet passageway for a longer period of time. When the sheet is thick or when the sheet is a slider, the condition of paper jam tends to occur more easily. Thus, the printing device cannot be used conveniently.